PIT 1 gene polymorphism and seasonality affect milk production traits in dairy cattle of Kashmir

Abstract

The study aimed at identifying the best genotypes for important candidate PIT 1 gene and seasonality influencing the yield and quality of milk, in the Jersey and Crossbred HF cattle population maintained at an organized farm in Mountain Livestock Research Institute, Manasbal, Kashmir. The Jersey and Crossbred HF cows (60 each) were genotyped for quality and yield traits. Milk samples (50 ml) were collected on weekly basis for quality evaluation for the years 2016-18, among all the four seasons of Kashmir. The milk quality traits studied were fat%, lactose%, protein%, SNF, density and ash. The quantity traits were average monthly milk yield, protein yield and fat yield. Genomic DNA was extracted using Phenol-chloroform method and association analysis was done. The PIT 1 exon VI (451 bp) was screened for polymorphisms using PCR-RFLP using HinfI restriction enzyme, revealing two genotypes (Pp and pp) for both the breeds. Allele ‘p’ was most frequently present in Crossbred HF cows (0.95) and Jersey cows (0.82). The genotype Pp in crossbred HF cows and pp in Jersey cows showed higher values for yield traits in all four seasons under study. In crossbred HF cows, the effect of genotype Pp was significant on fat% and SNF. The genotype pp effect was significant on fat% in Jersey cows. Winter and autumn seasons had significant effect on fat% in both breeds under study. Based on the study, it was concluded that breed, season, and genotype of the PIT 1 gene are highly associated with the milk quality and yield in the dairy cattle of Kashmir. Genome wide association studies are recommended for better understanding the effects of all genes on milk quality and quantity.